Spool halves have long been used in the hydraulic arts and are generally comprised of a body member having a cylindrical bore therein with one or more hydraulic fluid ports intersecting with the bore. A valve plunger is slidably and rotatably mounted within the bore and has one or more cylindrical spools which serve to open or close the ports as the plunger is moved within the bore.
Some of the spool valves have spools with notches appearing on at least one peripheral edge thereof so as to allow hydraulic fluid to move through the notches as fluid moves between the bore and the ports. When the spools are positioned so that the notches slightly overlap the ports, the flow of fluid can be finely metered as the plunger delicately moves the spools to a position where the notches overlap the periphery of the port.
When the valve is of a construction to permit the plunger to be rotated, it is necessary to have an annular groove created within the bore and in communication with the port so that it can be assured that the notches will be in direct contact with fluid flow. Without the annular grooves, the device would operate only if the notches were in direct communication with the fluid port.
A further shortcoming of existing spool valves is that the notches therein are machined into the peripheral edges thereof, and this is time consuming and expensive.
It is therefore a principal object of this invention to provide a spool valve with spools therein which are adaptable for both rotational and/or slidable movement within the bore of the valve.
A further object of this invention is to provide a spool valve which has a notched spool therein which can successfully operate without the use of an annular groove within the bore of the valve which is in communication with the fluid port.
A still further object of this invention is to provide a method of placing notches in the spool of a spool valve that is inexpensive and which does not require machining.
These and other objects will be apparent to those skilled in the art.